1. Field of the Invention
The invention relates to refrigeration systems, and particularly to refrigeration systems having two or more compartments which are to be cooled or maintained at different temperatures.
2. Discussion of the Background
Refrigeration systems having two or more compartments maintained at different temperatures are known for both domestic (household) and commercial (e.g., restaurants, stores, etc.) uses. Typically, it is desirable to maintain one compartment at a lower temperature than one or more other compartments such that various items can be maintained at appropriate temperatures. For example, a first compartment can be utilized for storing items at low temperatures, such as frozen foods, with a second compartment provided for storage at a temperature higher than that of the first compartment, for example a temperature suitable for fresh foods.
To achieve the different temperatures for the respective compartments, a single evaporator can be utilized for providing cold air to the respective compartments, with the respective temperatures determined based upon the amount of cold air provided for each compartment. However, it can be difficult to properly control the temperatures of each of the compartments with such an arrangement, particularly with changing ambient conditions and changes in the respective thermal loads of the compartments (e.g. door opening or introduction of warm food).
Systems have also been devised for two compartment refrigerators in which an evaporator is provided for each of the compartments. U.S. Pat. No. 5,150,583 to Jaster discloses an example of such an arrangement in which a pair of evaporators are provided for respective freezer and fresh food compartments. However, such an arrangement can be complicated in that the conditions of each of the evaporators must be controlled, thus increasing the complexity of the system, as well as increasing the cost to both manufacture and use the system. Accordingly, an improved refrigeration system is desired which can reliably cool two or more compartments economically and efficiently.